Local sources said the clashes broke out between fighters from the Brigades of Return, a group orginally linked to Palestinian Authority President Mohammad Abbas's Fatah group, and a rival militant organization.

The leader of the Brigades of Return, Ahmed Rasheed, and two of his brothers were killed in the clashes in the Mieh Mieh camp, the sources said.

It was not immediately clear what triggered the fighting, in which at least 10 people were wounded.

Fatah and a range of Islamist factions compete for influence in Mieh Mieh and the nearby Ain al-Hilweh, two of the 12 Palestinian camps in Lebanon that are home to more than 200,000 registered refugees.

Tensions in the camps and in Lebanon as a whole have been been exacerbated by the conflict in neighbouring Syria. More than a million Syrian refugees have poured into Lebanon along with many Palestinians, displaced by three years of war.